Spinner head



Jan. 31., .1956 W|KER 2,732,585

SPINNER HEAD Filed Feb. 12, 1952 5 Sheets-Sheet l INVENTOR ATTORNEY Jan.31, 1956 c. B. WICKER 2,732,585

SPINNER HEAD FiledFeb. 12, 1952 3 SheetS -Sheet 2 INVENTOR 0,4 5.W/CKf/P film KM ATTORNEY D. B. WICKER SPINNER HEAD Jan. 31, 1956 3Sheets-Sheet 3 Filed Feb. 12, 1952 INVENTOR flflA/B. W/CKF/P BY )p z E IATTORNEY United States Patent O SPINNER" HEAD Dan B- Wicken. Stamford,Cun-.,,assignor to American Cyaua id Company, New Yorlt N, 12;, a.corporation This invention relates to a spinner headfbr the extrusion ofa coagulable material" in themanufacture' of. artificial fibers. g

In producing artificial filaments'b t-lie spinning Qfsolutions of afiber-forming material, it frequently ha pens that the solution at:normal temperature, or when warmed only slightly, is so viscous that itcannot be extruded or spun satisfactorily because of. low'pullaway'speedfrom the face of'the spinneret' with a. resulting. low production rateper spinning. unit andexcessive power: consumption in extruding thethick dope through small orifices. The solution of this problem in some:instances resides in merelyheating a large bulk of the; spinningsolution or dope prior to pumping this'dopeto'thespinner head. Thistechnique is unsuitable forthewetspinning ofsolutions: of polymeric and.copolymeric acrylonitril'c in concentrated aqueous solutionsiofcertainsalts asidescribedin Cresswell Patent No. 2,558,730becauseiofobjectionable alterations in theproperti'es'ofsuch solutionsupon heating. for a relatively prolonged period of time. In addition theviscosity of these solutions is such, that;there is relatively littlemixing of the viscousdope while beingpumped through, a. relatively' longpipe to a spinneret; hence the'heat lbsti by. the peripheral portion ofthe dope stream in. its flow through the pipe resultsin lackofuniformityin the temperatures of various portionsor strataiof." thespinning solution. Such. lack of'uniform temperature becomes seriouswhena hot spinning dope must flow through conduits submerged in a coldspinning bath as used in the C'resswell" process: This etfectisintensified in the production oftow or staple fibers as. acorrespondingly larger amount of the dope passes through larger pipelines in spinning 5'00 to 5000 or more filaments per spinning header'ihcontrast to. the

30 to 240 filaments per unit typical of continuous filament yarnproduction. Withother; conditions constantiinthe Cresswell process, thesize; of fibers. extrudingfrom the orifices of a spinneret varies asaninverse function of'tlie viscosity of the spinning dope, and such.viscosity is,. of course, an inverse function of the ambient temperatureof each particular orifice; therefore a uniform temperature at thenumerous orifices. is essentialto theproduction of a strand or tow offibers of. uniform. diameten. Various heated spinning heads are known inthe.- art. hut these, without exception, have been found inadequate tor.the production of tow by the Cresswell process. since. none were able todeliver. the Spinning done with. suflicient thermal. uniformity toeachofamultiplicity ohorifices. for the production of uniformly sizedfibers and. none were capable of supplying the necessary. large quantityoi heat at a point close to thevspinneretfacer The. failure to. meet thelatter requirementmeant a considerablyv greater; num: ber of spinningunits wouldbe requiredfor any given: production rate thereby lowering.the manufacturing @lfi'r ciency. I 1 H 5 An object of the invention is;to provide an; improved. de vice for the extrusion of artificial;fibers;

Another object of the invention is to; ptcuide anz' have proved devicefor the spinning of an artificial fiber tow from: a viscous coagulablematerial.

A further object of the invention is to provide an improved" device forheating a reiatively large amount of a viscous dope to a uniformtemperature immediately prior to extrusion;

Other objects and advantages of the invention will be apparent to thoseskilledin the art from the description hereinbelow;

The present invention concerns a spinning headhaving a multiconduitindirectheat exchanger and a spinneret locatedadjacent" to the outletthereof. Other features of the invention include a projecting flangewhich transfers heat to the spinning dope immediately prior to itsextrusion, means for insulating the heat exchanger, upper andlower'condensatetrapsand'meansfor positioning the device in variouspositions; The invention accordingly comprisesthefeatures"ofconstruction, combinations of elements and' arrangernent ofparts, which will be exemplified in'the construction hereinafterset'forth, and the scope of the invention willbeindicated in the claims.

A better understanding of the nature and objects of theprcsent'inventionwill be had by reference to the accompanying drawingsin which:

Fig. 1 is a longitudinal sectional view through the centerof thespinningheadwith certain parts removed;

Fig; 2 is a fragmentary enlarged sectional view of the extrusion end ofthe apparatus taken-on the same plane as Fig: l;

Figs. 3; 4 and'5 aresomewhat diagrammatic elevation views of'thespi'nni'ngh-ead in various positions.

Referring now to Fig. 1 thespinner unit is mounted in the casing It)which i'sfastened to a shaft 12 by a cap screw 14 or other suitablemeans. Within this casing is an indirect heat exchanger 1'6 of" themultitubul'ar type known asa-shell and tube-heat exchanger. This heatexchanger consists ofshell" 18 and the inlet and outlet tubesheetsZOia-nd 22irespectivel'y; which are rigidly'secured to theshell 1Sby'brazing, welding or other suitable means. Suitable-access doors (notshown) are provided in casing 10 for the installation and' maintenanceof'the equipment contained therein.

Theshell is 7%r inches'long and 3 inches in diameter. There-are 3Ttubes: 24- with inside and outside diameters of% inch and- 7 inch,respectively, mounted in the tube sheets. A heater of this size has beenfound to be very satisfactory in the Cresswell" process in extruding upto about 5000 filaments of acrylbnitriie copolymer tow through orificeshaving a diameter of 65 microns. The size, number and lengthof'tubes'may, of course, be varied to accommodate greater or smallernumbers or sizes of A fluid medium is used for heating this multitubulanheaterand it may be either a liquid, vapor or gaseous'substance. Steamisgenerally preferred for the purpose, especially for spinning fibersfrom acrylonitrile polymers and copolymers at about to C.

The short shaft 12 extends through the casing 10 and projects outsideinto bearings (not shown) mounted in suitable supports on both sides of"the casing. The in: coming heating medium is' introduced throughsuitable channels in one of these hearings which communicate withthelongitudinalpassage 26in the'center of shaft 12. Thispassage leads tothe channel 28 and tube or pipe 39" which carries the steam to. theinlet 32 located near the exittube' sheet 22". From this point theheating medium flows. over: the exterior surfaces of the tubesthroughout the shell and passes to the left; it leaves the heat ex-'changer: through oneor both of the outlets 34 which arelocated at' thetop and bottom. of shell 18 in close proximity to inlet tube sheet; 20.:When: steam is: employed for heating,. the thermostatic steeurrv traps36' and 38. are Rrovidethfor; separating. condensate. fromthesteamaLines 40 and 42 respectively connect these traps with the exhaust line44 which communicates with passage 46 and longitudinal hole 48 in shaft12. Channel 48 is in communication with a suitable annular passage inthe bearing or bearing cap (not shown) thus providing for removal of thecold heating medium or condensate at any angular position of the spinnerhead. The coagulable polymeric material or spinning dope from which thefibers are formed is pumped into the spinning head through a centralchannel in the opposite bearing or bearing cap (not shown) and passages(not shown) similar to intake channels 26 and 28. These dope feedpassages communicate with the tube 50 and inlet header 52 which isbolted or otherwise secured to the inlet tube sheet 20. Under theinfluence of the uniform pressure in header 52, the spinning dope flowsat uniform velocities through the tubes 24 of uniform length anddiameter to the outlet tube sheet 22. The tubes are of relatively smalldiameter and are heated evenly by the steam, hence all'portions of allof the streams flowing through the exit tube sheet are at substantiallythe same temperature even in the case of a viscous polyacrylonitriledope which is prone to form strata of different temperatures. It will benoted that the flow is countercurrent to the flow of the heating mediumfor maximum heat transfer efliciency with noncondensing heating media.The heat exchanger 16 and its accessories are fastened to the casingwith an appropriate number of cap screws 54 and the joint is sealed witha moisture-proof rubber gasket 56 which also serves to reduce the lossof heat by conduction from the heat exchanger to the casing.

Turning now to Fig. 2 the heated dope leaving the tubes 24 enters achamber 58 bounded by the tube sheet 22 with its integral cylindricalflange or fin 60 and the spinneret 62 which is provided with a largenumber of tiny orifices 64 which are shown only schematically. Withinthe chamber 58 is a filtering device which is made up of a fabric filter66 consisting of about four layers of woven nylon or other textilematerials which are relatively unatfected by the solvent and ambientthermal conditions. The number of layers of filter cloth depends on thecoarseness of the weave and size of the interstices. If a tightly wovenor finely woven fabric is available, one layer may provide asatisfactory filter. The cloth is held in place by a stainless steelwire screen 68 to which is attached an annular or ring separator 70 madeof nylon or other suitable corrosion-resistant material and providedwith a series of deep serrations or notches 72 on both sides of the ringin order to permit the free flow of the spinning dope between theinterior and the exterior of the ring on both sides thereof. Thefunction of ring 70 is to keep the filter spaced from the spinningorifices 64 to avoid blocking any of the holes. In mounting thespinneret assembly on the spinner header a rubber gasket 74 is placed onthe projecting flange 60. This is followed by the layers of nylon cloth66 and another rubber gasket 76. Next the screen 68 with' its attachedspacer 70 are held against the cloth 66 while the spinneret 62 is pushedinto place on the flange 60. The spinneret is fastened in place by theclamp ring 78 which is desirably fashioned out of cloth laminated with aplastic, such as a phenolformaldehyde condensation product. For extrastrength it is desirable to mold a flat metallic plate insert 80 intothe clamp ring. The clamoring issecured by the circular row of capscrews 82 which engage threads in the annular boss 84 in casing 10. Inorder to seal the casing, which is particularly necessary when theassembly is to be operated in a submerged position, the seals 86 aroundthe spinneret as well as 88 and 90 around the boss 84 are provided. Eachof these consists of a deformable rubber ring placed in an annulargroove of suitable size. It will be noted that this constructionprovides a sizable annular pocket or air space 92 between casing 10 andclamp ring 78. This as well as the low thermal conductivity of theplastic used in the ring serve to effectively insulate the heatexchanger 16 against heat losses except for the amount of heat which isnecessarily lost through contact of the face of spinneret 62 with thecoagulating medium. In this connection it should be observed that theprojecting fin 60 serves to conduct a substantial amount of heat to thespinning solution in the spinneret 62 in order to maintain the dope atspinning temperature until it is in actual contact with the coagulatingmedium.

The various positions of the spinner header are illustrated in Figs. 3,4 and 5. In Fig. 3 the header is locked back out of the coagulating bath94 by means of the double hook 96 which is pivotally attached to thecasing 10 by means of the pivot 98. The hook 96 is provided with twoslots 100 and one of these engages the crossbar 102 which is fastened tothe frame member 104. This frame member 104 is riveted or otherwisesecurely attached to the tank 106. Other fastening or holding means,such as latches, hooks on chains or ropes, gear arrangements, etc. arecontemplated as substitutes for the rigid hooks 96.

In preparing the header for extrusion operations, it is moved to theposition shown in Fig. 4 by engaging the hook 96 with the crossbar 108which is also attached to the frame 104. This unit is brought to theoptimum operating temperature and the entire spinning dope feed systemis purged free of air in this position; inasmuch as the spinneret faceis tilted slightly downward, the extruded dope falls free of theoperating face of the spinner head instead of flooding over it. The dopeextruded at this time, while purging the spinner head, may be caught inany suitable container in order to avoid having random bits ofcoagulated polymer circulating through the bath 94. After beingthoroughly purged and heated, the header is swung into the operatingposition shown in Fig. 5 and fixed in the position by the engagement ofhook 96 with a crossbar 110 which extends through the bath and isfastened to the tank in any suitable manner.

When the spinning unit is in the inverted or starting-up position ofFig. 4 the condensate from the steam drains out through the trap 36which is in the lower position while the upper trap 38 performs theextremely useful function of bleeding air out of the heating system.However, in the normal operating positions shown in Figs. 1 and 5, thecondensed liquid drains out through the lower trap 38 andtrap 36 doesnot function unless some air has gotten into the system.

In the aforementioned Cresswell process polymers and copolymers ofacrylonitrile dissolved in a suitable solvent, such as a concentratedaqueous solution of sodium thiocyanate, is extruded at a temperature ofabout 60 to 100 C. into a liquid coagulating bath of a relatively diluteaqueous sodium thiocyanate solution maintained below 10 C. andpreferably within a few degrees above or below 0 C.- In the productionof tow the extrusion temperature may run as high as about 110 C.;however it is preferred to extrude the filaments of tow at 95 C. into aliquid coagulant maintained at 0 C. The tempera- .tures of that processare critical therefore insulation of the multitubular heat exchanger isunusually important in minimizing the transfer of heat to the lowtemperature coagulating bath and in reducing both the heating and therefrigeration loads. From the construction described herein it isapparent that the spinneret has been completely shielded'o'r insulatedfrom the cold coagulant except for the spinneret face which mustnecessarily be exposed. The construction described also reduces the heatlost through the side and flange of the spinneret to the chilledcoagulating solution as these members are shielded by the ring 78 madeof a plastic material of low thermal conductivity. Minimizing this heatloss results in the outermost-or peripheral orifices 64 being maintainedat substantially the same temperature as the inner orifices. Becauseofthis, fibers of substantially uniform size are formed in all of theorifices rather than undersized filaments-at somewhat cooler outerorifices.

A number of advantages accrue from the pivotal mounting of the spinnerhead. In the inverted position the device is readily accessible foradjustment or maintenance, and the passages and tubes carrying thespinning solution may be purged free of air and brought up totemperature without interfering with the adjacent units in a battery ofthese spinning heads. At this time all of the extruded dope may bereadily collected in any suitable container; then the unit may bereadily and quickly swung into operating position by releasing the hookfrom crossbar 108 and fastening it on crossbar 110. In approaching theoperating position it will be noted that the spinning head is swingingin the direction of extrusion of the filaments; in other words, the headis approaching its operating position from the rear. This has been foundhighly desirable in avoiding interference with the adjacent spinningunits in the battery as the likelihood of dribbling dope into fibersbeing taken off of the adjacent spinning positions is negligible.

Although the device of the present invention is particularly useful inthe wet spinning of high-viscosity solutions of polymers and copolymersof acrylonitrile, its utility is not limited either to polyacrylonitrileor to wet spinning. It can be employed in the wet spinning of otherartificial fiber dopes and also in dry spinning operations wherein a hotsolution of polyacrylonitrile or other fiber forming material in anorganic or other suitable solvent is extruded into a heated atmosphereto evaporate the solvent and to coagulate the filamentary material.

While there are above disclosed but a limited number of embodiments ofthe structure of the invention herein presented, it is possible toproduce still other embodiments without departing from the inventiveconcept herein disclosed, and it is desired therefore that only suchlimitation be imposed on the appended claims as are stated therein orrequired by the prior art.

Having disclosed my invention in detail, what I claim as new and desireto secure by Letters Patent is:

1. A device for the extrusion of filaments of a coagulable materialwhich comprises an indirect heat exchanger having a shell provided withwalls supporting a plurality of conduits in which the coagulablematerial is heated while passing therethrough by heat transferredthrough the conduits from a heating medium circulating through the shellon the outside of the conduits, a cup-shaped spinneret provided withorifices through which the heated coagulable material is extruded in theform of filaments and a projecting flange of high thermal conductivityattached to a conduit outlet wall and extending into the spinneret inorder to supply heat from the heating medium to the coagulable materialimmediately adjacent to the spinneret orifices.

2. A device according to claim 1 in which the heat exchanger issubstantially enclosed in a casing separated therefrom in such manner asto provide heat-insulating space surrounding a major portion of theexterior of the heat exchanger.

3. A device according to claim 1 in which said device is swingablymounted and provided with means for fixing said device in apredetermined position.

4. A device according to claim 1 in which the heating medium isintroduced from a supply means through an inlet near the conduit outletwall and circulated through the shell to an outlet near the conduitinlet wall countercurrently to the flow of coagulable material.

5. A device according to claim 1 in which condensate traps are providedadjacent the opposite sides of the shell for the removal of thecondensate of a condensable heating medium.

6. A device accordingto claim 1 in which a condensable heating medium iscirculated through the shell countercurrently to the flow of coagulablematerial by means including a heating medium inlet near the conduitoutlet wall and condensate traps adjacent opposite sides of the shellnear the conduit inlet wall for the removal of the condensate of theheating medium.

7. A device for the extrusion of filaments of coagulable material whichcomprises a shell and tube indirect heat exchanger provided with tubesheets supporting a plurality of substantially parallel tubes in whichthe coagulable material is heated While passing therethrough by heattransferred through the walls of the tubes from a condensable heatingmedium circulated countercurrently through the shell on the outside ofthe tubes by means including a heating medium inlet near an outlet tubesheet and condensate traps near an inlet tube sheet for the removal ofcondensate of the heating medium, the condensate traps being locatedadjacent the top and bottom of the shell when the tubes are inhorizontal alignment, a cup-shaped spinneret provided with orificesthrough which the heated coagulable material is extruded in the form offilaments, a projecting flange of high thermal conductivity attached tothe outlet tube sheet and extending into the spinneret in order tosupply heat from the heating medium to the coagulable materialimmediately adjacent to the spinneret orifices, a swingably-mountedcasing substantially enclosing the heat exchanger and separatedtherefrom in such manner as to provide heat-insulating space surroundinga major portion of the exterior of the heat exchanger, and means forfixing the casing in a predetermined position.

References Cited in the file of this patent UNITED STATES PATENTS1,176,612 Snider Mar. 21, 1916 1,450,131 Borzykowski Mar. 27, 19231,918,816 Lecomte July 18, 1933 2,272,880 Greenup Feb. 10, 19422,369,553 Fields Feb. 13, 1945 2,425,782 Bludworth et al. Aug. 19, 19472,514,189 Spencer et al July 4, 1950 2,586,970 McDermott Feb. 26, 1952

1. A DEVICE FOR THE EXTRUSION OF FILAMENTS OF A COAGULABLE MATERIALWHICH COMPRISES AN INDIRECT HEAT EXCHANGER HAVING A SHELL PROVIDED WITHWALLS SUPPORTING A PLURALITY OF CONDUITS IN WHICH THE COAGULABLEMATERIAL IS HEATED WHILE PASSING THERETHROUGH BY HEAT TRANSFERREDTHROUGH THE CONDUITS FROM A HEATING MEDIUM CIRCULATING THROUGH THE SHELLON THE OUTSIDE OF THE CONDUITS, A CUP-SHAPED SPINNERET PROVIDED WITHORIFICES THROUGH WHICH THE HEATED COAGULABLE MATERIAL IS EXTRUDED IN THEFORM OF FILAMENTS AND A PROJECTING FLANGE OF HIGH THERMAL CONDUCTIVITYATTACHED TO A CONDUIT OUTLET WALL AND EXTENDING INTO THE SPINNERET INORDER TO SUPPLY HEAT FROM THE HEATING MEDIUM TO THE COAGULABLE MATERIALIMMEDIATELY ADJACENT TO THE SPINNERET ORIFICES.